1. Technical Field
The present application relates to charge pump circuitry, including charge pump circuitry used in integrated circuits.
2. Related Art
Integrated circuits, sometimes referred to as microchips or semiconductor devices, are in widespread use and can be found in almost all electronic equipment in use today. The packaging of an integrated circuit can vary, but will include at least one contact point, simply referred to herein as a “pin,” that allows for electronic communication between circuitry within the integrated circuit and circuitry external to the integrated circuit. A typical integrated circuit will include a pin for receiving an external supply voltage VDD that is predetermined and configured to remain at an at least somewhat constant voltage level during operation.
Some integrated circuits are configured to use a voltage level that exceeds the supply voltage VDD for at least some operations. For example, some integrated circuits are memory devices that use a voltage greater than supply voltage VDD for read and/or write operations. Such integrated circuits will often include a charge pump. A charge pump is a circuit that can provide a voltage that exceeds the supply voltage VDD.
For example, FIG. 1 shows a block diagram of voltage pumping circuitry of a conventional integrated circuit 100. The integrated circuit 100 includes a pump circuit 102 and a clock signal circuit 104, which are both internal to the integrated circuit 100. The pump circuit 102 and clock signal circuit 104 receive a supply voltage VDD provided by a power supply external to the integrated circuit 100. The clock signal circuit 104 generates complementary clock signals CLK1 and CLK2 and provides the clock signals CLK1 and CLK2 to the pump circuit 102. The pump circuit 102 receives the supply voltage VDD and the clock signals CLK1 and CLK2 and generates a pumping voltage VPUMP that has a voltage level that exceeds the voltage level of the supply voltage VDD. The pumping voltage VPUMP can thus be provided to other circuitry not shown of the integrated circuit 100.
In some cases, the integrated circuit 100 may be a type of integrated circuit that can be used with a variety of different electronic systems. For example, the integrated circuit 100 may be an electronic memory device. The frequency of the clock signals CLK1 and CLK2 affects the performance of the integrated circuit 100 as well as the power consumption of the integrated circuit 100. These affects extend to the performance and power consumption of the electronic system that incorporates the integrated circuit 100. Since the particular frequency of the clock signals CLK1 and CLK2 will depend on the configuration of the clock signal circuit 104, the frequency of the clock signals CLK1 and CLK2 is determined and set during the design and manufacturing of the integrated circuit 100. Thus, the integrated circuit 100 may be less than optimal for some systems.
Also, there are additional drawbacks to including an internal clock generator such as clock circuit 104 in the integrated circuit 100. For example, the internal clock circuitry occupies a large area and has a relatively large peak current.
Thus, it is desirable to find alternative approaches for increasing the flexibility of integrated circuits in order to allow for good performance with a variety of operating environments.